As known, the real world is analog while the world of electronics is moving more and more towards digital solutions. There are advantages and disadvantages of the use of analog or digital solutions, in particular with analog techniques, the lowest power consumption and a behaviour close to the real world are obtained. Circuits that perform artificial intelligence functions require simple operations that can be implemented in the analog domain. Furthermore, the use of medium-resolution analog-to-digital converters allows the transition to the digital world thus allowing a mixed implementation of required functions. This presentation discusses analog and mixed circuits for the construction of circuits for artificial intelligence.